Help with a DMD patch

[Igor Stepanov]

On Saturday, 16 March 2013 at 21:49:33 UTC, Vladimir Panteleev 
wrote:
> On Saturday, 16 March 2013 at 21:42:31 UTC, Igor Stepanov wrote:
>> On Saturday, 16 March 2013 at 21:21:51 UTC, Vladimir Panteleev 
>> wrote:
>>> On Saturday, 16 March 2013 at 21:15:32 UTC, Igor Stepanov 
>>> wrote:
>>>> What do the lines el_combine? I do not see them in the code 
>>>> structure comparison.
>>>
>>> Greetings Igor,
>>>
>>> The el_combine calls are supposed to ensure correct order of 
>>> evaluation.
>>>
>>> I based that code from this fragment:
>>>
>>> https://github.com/D-Programming-Language/dmd/blob/635c6b07/src/e2ir.c#L2702
>>
>> Visually, it should work :)
>> I would try to make sure that the various components of 
>> expression are correctly calculated. In particular, I am 
>> concerned the calculation of the length of a dynamic array. 
>> You can try to do so, that would return the length of the 
>> entire expression.
>> / ***** In DMD ***** /
>> if (t1->ty == Tarray)
>> {
>>  retrun el_una(I64 ? OP128_64 : OP64_32, TYsize_t, 
>> el_same(&earr1));
>> }
>> / ***** In D ***** /
>> int[] arr = [1,2,3];
>> int[] arr3 = [1,2,3,4,5];
>> size_t len = cast(size_t)(arr == arr3);
>> assert(len == arr.length);
>
> Dynamic arrays work perfectly, it's the static ones I'm having 
> trouble with... particularly, when they're being returned from 
> a function.
>
> From what I can tell, the situation is that I can neither copy 
> them using el_same (it neither makes sense, as the arrays can 
> be large, nor does the compiler let me to), nor can I take 
> their address, because the code generator fails to process an 
> OPaddr elem when its child is a function call. However, the 
> same thing seems to work when calling the runtime function for 
> array equality (the current implementation)...

Probably a stupid question, but why do you want to use el_same? 
As I understand it, el_same creates a copy. Why not use the 
original, if we know that it will not change anything.